<!DOCTYPE HTML>
<html>
<head>
  <meta charset="utf-8">
  <title>Toplevel data navigation</title>
</head>
<body>
test2: data: URI in iframe tries to window.open(data:, _blank);<br/>
<iframe id="testFrame" src=""></iframe>
<script>
  let DATA_URI = `data:text/html,<body><script>
    var win = window.open("data:text/html,<body>toplevel data: URI navigations should be blocked</body>", "_blank");
    setTimeout(function () {
      var result = win.document.body.innerHTML === "" ? "blocked" : "navigated";
      parent.postMessage(result, "*");
      win.close();
    }, 1000);
    <\/script></body>`;

  window.addEventListener("message", receiveMessage);
  function receiveMessage(event) {
    window.removeEventListener("message", receiveMessage);
    // propagate the information back to the caller
    window.opener.postMessage(event.data, "*");
  }
  document.getElementById('testFrame').src = DATA_URI;
</script>
</body>
</html>
